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.TH MBRLEN 3C "February 17, 2023"
.SH NAME
mbrlen, mbrlen_l \- get number of bytes in a character (restartable)
.SH SYNOPSIS
.nf
#include <wchar.h>

\fBsize_t\fR \fBmbrlen\fR(\fBconst char *restrict\fR \fIs\fR, \fBsize_t\fR \fIn\fR, \fBmbstate_t *restrict\fR \fIps\fR);
.fi
.LP
.nf
#include <wchar.h>
#include <xlocale.h>

\fBsize_t\fR \fBmbrlen_l\fR(\fBconst char *restrict\fR \fIs\fR, \fBsize_t\fR \fIn\fR, \fBmbstate_t *restrict\fR \fIps\fR,
    \fBlocale_t\fR \fIloc\fR);
.fi
.SH DESCRIPTION
If \fIs\fR is not a null pointer,  \fBmbrlen()\fR and \fBmbrlen_l()\fR determine
the number of bytes constituting the character pointed to by \fIs\fR.
The call
.nf
.IP
\fBmbrlen\fR(\fIs\fR, \fIn\fR, \fIps\fR);
.fi
.LP
is equivalent to:
.nf
.IP
mbstate_t internal;
\fBmbrtowc\fR(NULL, \fIs\fR, \fIn\fR, \fIps\fR != NULL ? \fIps\fR : &internal);
.fi
.LP
If \fIps\fR is a null pointer, the \fBmbrlen()\fR and \fBmbrlen_l()\fR
functions use their own
internal \fBmbstate_t\fR object, which is initialized at program startup to the
initial conversion state.   Otherwise, the  \fBmbstate_t\fR object pointed to
by \fIps\fR is used to completely describe the current conversion state of the
associated character sequence. The implementation will behave as if no function
defined in the Reference Manual calls \fBmbrlen()\fR.
.LP
The behavior of \fBmbrlen()\fR is affected by the \fBLC_CTYPE\fR category of the
current locale.  See \fBenviron\fR(7). The behavior of \fBmbrlen_l()\fR does not
use the current environment and instead uses the locale specified by \fBloc\fR.
.SH RETURN VALUES
The \fBmbrlen()\fR and \fBmbrlen_l()\fR functions return the first of the
following that applies:
.sp
.ne 2
.na
\fB\fB0\fR\fR
.ad
.RS 17n
If the next \fIn\fR or fewer bytes complete the character that corresponds to
the null wide-character.
.RE

.sp
.ne 2
.na
\fB\fBpositive\fR\fR
.ad
.RS 17n
If the next \fIn\fR or fewer bytes complete a valid character; the value
returned is the number of bytes that complete the character.
.RE

.sp
.ne 2
.na
\fB\fB(size_t)\(mi2\fR\fR
.ad
.RS 17n
If the next \fIn\fR bytes contribute to an incomplete but potentially valid
character, and all \fIn\fR bytes have been processed. When \fIn\fR has at least
the value of the \fBMB_CUR_MAX\fR macro, this case can only occur if  \fIs\fR
points at a sequence of redundant shift sequences (for implementations with
state-dependent encodings).
.RE

.sp
.ne 2
.na
\fB\fB(size_t)\(mi1\fR\fR
.ad
.RS 17n
If an encoding error occurs, in which case the next \fIn\fR or fewer bytes do
not contribute to a complete and valid  character.  In this case, \fBEILSEQ\fR
is stored in \fBerrno\fR and the conversion state is undefined.
.RE

.SH ERRORS
The \fBmbrlen()\fR and \fBmbrlen_l()\fR functions may fail if:
.sp
.ne 2
.na
\fB\fBEINVAL\fR\fR
.ad
.RS 10n
The \fIps\fR argument points to an object that contains an invalid conversion
state.
.RE

.sp
.ne 2
.na
\fB\fBEILSEQ\fR\fR
.ad
.RS 10n
Invalid character sequence is detected.
.RE

.SH ATTRIBUTES
See \fBattributes\fR(7) for descriptions of the following attributes:
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
Interface Stability	See below.
_
MT-Level	MT-Safe
.TE

.LP
The
.B mbrlen()
function is Standard.  The
.B mbrlen_l()
function is Uncommitted.
.SH SEE ALSO
.BR mbrtowc (3C),
.BR mbsinit (3C),
.BR newlocale (3C),
.BR setlocale (3C),
.BR attributes (7),
.BR environ (7),
.BR standards (7)
.SH NOTES
If \fIps\fR is not a null pointer, \fBmbrlen()\fR uses the \fBmbstate_t\fR
object pointed to by \fIps\fR and the function can be used safely in
multithreaded applications, as long as \fBsetlocale\fR(3C) is not being called
to change the locale or a per-thread locale has been installed on the calling
thread with \fBuselocale\fR(3C). If \fIps\fR is a null pointer, \fBmbrlen()\fR
uses its internal \fBmbstate_t\fR object and the function is Unsafe in
multithreaded applications.
